Saint Helier climate — normals and trends
Saint Helier (Jersey) has a temperate oceanic climate (Cfb) under the Köppen-Geiger classification. Its mean annual temperature is 11.8 °C and it receives 963 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is August (17.1 °C on average) and the coldest is February (7.1 °C). Rainfall peaks in November.
Saint Helier averages 2 frost days, 0 hot days (≥ 30 °C) and 152 rainy days per year.
Saint Helier has warmed by +1.2 °C between 1940 and 2025, or +0.14 °C per decade. This trend is statistically significant.
The number of frost days there went from about 4 to 0 per year over the period.
The hottest day of the period reached 28.2 °C (on 5 August 2003) and the coldest -6.0 °C (on 13 January 1987).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
Saint HelierSt Helier
- coords
- 49.19°, -2.10°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
11.8°C
Average daily high
12.9°C
Average daily low
10.9°C
Annual rainfall
963mm
Sunshine / day
8.9h
Mean relative humidity
81%
Average peak wind
33.2km/h
Seasonal range
10.0°C
Frost days (< 0 °C)
2 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
152 d/yr
Annual snowfall
4.4 cm
Average feels-like high
9.9 °C
Average feels-like low
6.4 °C
Average peak gust
44.8 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
12.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.2 °C
since 1940
+0.1 °C per decade · r² = 0.34 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
28.2 °C
5 August 2003
Coldest day
-6.0 °C
13 January 1987
Wettest day
54 mm
8 October 1997
Windiest day
98.3 km/h
16 October 1987
Strongest gust
145.1 km/h
16 October 1987
Hottest feels-like
30.7 °C
5 August 2003
Coldest feels-like
-15.3 °C
13 January 1987
Snowiest day
13.9 cm
11 March 2013
Sunniest day
15.8 h
19 June 2025
Normals computed over complete calendar years 1940–2025.
A specific year
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Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 8.6 °C | 0.0 °C | 183 mm | +77 mm |
| Feb | 8.7 °C | +0.5 °C | 54 mm | -29 mm |
| Mar | 10.2 °C | +1.0 °C | 38 mm | -31 mm |
| Apr | 12.9 °C | +2.3 °C | 47 mm | -6 mm |
| May | 14.7 °C | +1.7 °C | 28 mm | -25 mm |
| Jun | 17.7 °C | +2.3 °C | 43 mm | -2 mm |
| Jul | 18.8 °C | +1.5 °C | 74 mm | +26 mm |
| Aug | 19.7 °C | +1.7 °C | 36 mm | -22 mm |
| Sep | 17.6 °C | +0.3 °C | 113 mm | +33 mm |
| Oct | 15.8 °C | +0.7 °C | 127 mm | +16 mm |
| Nov | 13.3 °C | +1.3 °C | 99 mm | -33 mm |
| Dec | 10.5 °C | +0.6 °C | 118 mm | -9 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Saint Helier?
Saint Helier has a temperate oceanic climate (Köppen Cfb). Over 1940-2025, the average annual temperature is 11.8 °C and it receives 963 mm of precipitation per year.
What is the hottest day ever recorded in Saint Helier?
The hottest day measured in Saint Helier between 1940 and 2025 was 5 August 2003, reaching 28.2 °C.
What is the coldest day in Saint Helier?
The coldest day measured in Saint Helier between 1940 and 2025 was 13 January 1987, at -6.0 °C.
Does it snow in Saint Helier?
Yes. Saint Helier gets on average 4.4 cm of snow per year and has around 2 frost days.
Has the climate of Saint Helier warmed?
Yes: Saint Helier warmed by +1.2 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Saint Helier?
The wettest day measured in Saint Helier between 1940 and 2025 was 8 October 1997, with 54 mm of rain in 24 hours.
What was the windiest day in Saint Helier?
The windiest day measured in Saint Helier between 1940 and 2025 was 16 October 1987, with winds reaching 98.3 km/h.
What is the warmest month in Saint Helier?
The warmest month in Saint Helier is August (17.1 °C on average); the coldest is February (7.1 °C).
How much does it rain in Saint Helier?
Saint Helier receives on average 963 mm of precipitation per year, spread over about 152 rainy days.
Is it sunny in Saint Helier?
Saint Helier gets on average 8.9 hours of sunshine per day, roughly 3,249 hours per year over 1940-2025.
What is the biggest single-day snowfall in Saint Helier?
The heaviest 24-hour snowfall measured in Saint Helier between 1940 and 2025 was 11 March 2013, with 13.9 cm.
Are there tropical nights in Saint Helier?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Saint Helier.
What was the most extreme apparent temperature in Saint Helier?
In Saint Helier, between 1940 and 2025, the highest apparent temperature reached 30.7 °C on 5 August 2003, and the lowest was -15.3 °C on 13 January 1987.
Compare Saint Helier with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Saint Helier